Log-structured storage systems are used to quickly write data to disk. In a conventional implementation using traditional rotating platter magnetic hard disk drives, it is beneficial to queue up writes in a buffer and then write the entire buffer to a single location on disk once the buffer is full as a log segment on disk. Individual blocks of the log segment may then be logically inserted into a map tree in order to provide logical block addressing. Since random writes are essentially turned into sequential writes to the log segment, this approach allows for increased write speed for random writes, due to the fact that random writes require many seek operations, which are comparatively slow on traditional rotating platter magnetic hard disk drives.
In order to provide fault-tolerance against power failures, the buffer is queued up in non-volatile memory, such as battery-backed RAM. This allows write back caching to be employed with fault tolerance, improving performance without the risk of a power failure.